Apparatus for burning certain fuels



APPARATUS FOR BURNING CERTAIN FUELS Filed Nov. 16, 1932 xiii A Inwentor E-wbfi M Gttorneg Patented Apr. 17, 1934 APPARATUS FOR BURNING CERTAIN FUELS Fred J. Postel,

Milwaukee, Wis.

Application November 16, 1932, Serial No. 642,875

3 Claims.

The invention relates to furnaces and more particularly to a method and apparatus for efficiently burning certain kinds of coal in those types of furnaces in which the fuel is carried through the furnace on a travelling or chain grate stoker.

Eastern bituminous coals have a decided coking or caking action and when burned on chain grate stokers the fire near the front of the furnace crusts over thereby greatly restricting the air supply to this part of the furnace. The result is that the front of the furnace acts like a gas producer. Combustible gases are driven off but as there is an insufficient supply of air in that part of the furnace, these ga es pass on through the boiler and up the stack without being utilized and in spite of the fact that there may be an excess of air at the rear of the furnace. Thus it happens that an analysis of the flue gases may disclose an excess of oxygen and at the same time a serious amount of carbon monoxide.

Furthermore, the incomplete combustion resulting from the coking of the fire carries an excessive amount of combustible over into the ash pit. If this kind of coal is used at all on chain grate stokers it is necessary to break up this crust by hand using a slice bar for the purpose. To be effective, the crust must be broken uniformly throughout the coking zone and without undue disturbance of the fire; otherwise there will be holes in the fire with the attendant evils of excess air in those spots. If the fire is agitated too much there will furthermore be excessive smoke. Thus, it is apparent that the best results cannot be obtained by the use of a slice bar and from an operating standpoint any mechanical means that contact with the fire bed is also not desirable.

According to the present invention, I have provided a method of agitating the fire sufficiently to break the crust by subjecting the fire bed in the coking zone to the action of a series of intermittently applied steam jets uniformly distributed in the coking zone and of suflicient pressure to break the crust and I have also provided means for regulating and controlling these steam jets.

The invention further consists in the several features hereinafter set forth and more particularlydefined by claims at the conclusion hereof.

In the drawing, Fig. 1 is a vertical sectional view through a furnace embodying apparatus for carrying out the invention;

Fig. 2 is a detail transverse sectional view taken on the line 22 of Fig. 1;

Fig. 3 is a detail enlarged view of oneof the steam nozzles.

' In the drawing, the numeral 5 designates the furnace, the detailed construction of which we are not here concerned with except that it be one in which the fuel is introduced and carried along during its combustion process upon a travelling or chain grate stoker 6 whose articulated sections 7 pass over the rotary supports 8 and 9, the member 9 having a shaft 10 adapted to be driven by any suitable power drive.

Near the front of the furnace and more particularly in the region marked A in Fig. 1, fuel, such as Eastern bituminous coal, will coke or cake so that the air supply to the fire is greatly restricted with the resulting disadvantages heretofore pointed out. Toprevent this action I provide for subjecting this section of the fire to the action of a plurality of relatively high pressure steam jets applied immediately below the travelling grate so that the pressure or kinetic energy or" the steam acts to break up the crust.

As herein shown, the steam is supplied from a pipe 12 which may be provided with a manually operable shut off valve 13 and is also provided with a mechanically operated valve 14 of the ordinary whistle valve type. Beyond this valve, branch pipes 15 are provided each having a manually operable shut off valve 16 and a pipe section 17 positioned to extend transversely of the furnace and beneath the upper run of the grate.

Each of the pipes 17 has extending up from it at spaced points the distributor pipes 18, each of which has a nozzle member 19 at its upper end, such as shown in Fig. 3, having the spray openings 20 formed therein. It will be noted that the pipe sections 1'7 are spaced apart and it is also preferred to arrange the pipes 18 for one section in staggered relation to those of any adjoining section so as to secure a uniform distribution of the steam jets upon the fire as it moves through the coking zone.

The steam is supplied to the pipe section 17, and hence the nozzles 19, intermittently through the controlled action of the valve 14. This valve it has been noted is of the ordinary whistle valve type in which the valve is normally closed but can be opened by the pressure of the operating lever 21 on the exposed end 22 of the stem of the valve. This lever is pivoted intermediate its ends at 23 and is operatively connected by a spring 24 to one arm of a lever 25 pivoted at 26 and having a weight 27 adjustably mounted on its other arm.

The lever 21 is intermittently operated through the intermittent reciprocations of a rod 28 slidably mounted in spaced guides 29 and provided with spaced pins 30 adjacent the lever 25, a weight 31 at its lower end and an arm 32 carrying a roller 33 intermittently engaged by the tripping cam or star-wheel 34 mounted on the stoker shaft 10.

Thus, as the shaft 10 makes one revolution, the cam 34 produces several intermittent reciprocations of the rod 28, said cam acting to move said rod upwardly while the weight 31 acts on said rod to produce a quick return movement. During the upward movement of the bar 28, the lower of the pins 30 engages the lever 25 and swings it counterclockwise so that the weight 27 may also act upon said lever and through the spring 24 exert an upward pull upon the lever 21 and thus move said lever quickly to open the valve 14 which stays open until the bar 28 under the action of the weight 31 descends and brings the upper of the pins 30 into engagement with the lever 25 to swing the same from its valve opening position to the position shown in Fig. 1. It is also to be noted that the upper of the pins 30 may act as a stop to limit the swing of the lever 25 in its valve opening position.

Each time the valve 14 is opened, the steam is admitted to the nozzles 19 to break up the crust as previously described and one or more of the sets of nozzles may be cut out by operating the shut off valve or valves 16.

It is also to be noted that in the usual chain grate stoker, part of the grate bars are staggered relative to others so that the nozzle pipes 18 arranged as in Fig. 2 will take care of this condition, and the inclined spray holes 20 will also insure at least one jet blowing through the grate in case the other is obstructed.

I desire it to be understood that this invention is not to be limited to the details above described except in so far as the same may be included in the appended claims.

What I claim as my invention is:

1. In a furnace, the combination with a chain grate stoker having a coking zone, of a plurality of nozzles arranged in spaced relation immediately below the upper run of the stoker and in the region of the coking zone of the fuel for discharging steam against the fuel to break up the crust formed in said zone, and means for intermittently supplying steam to said nozzles as the fuel progresses through said zone.

2. In a furnace the combination with a chain grate stoker having a coking zone, of a steam supply pipe, a valve in said pipe, branch pipes beyond said valve including pipe sections transversely disposed relative to said stoker and arranged in spaced relation, spaced apart distributor pipes communicating with each of said pipe sections, a nozzle at the upper end of each of said distributor pipes and disposed adjacent the bottom side of the upper run of said stoker to deliver steam against the fuel bed in the coking zone to break up the crust thereof, and means for intermittently operating said valve.

3. In a furnace, the combination With a chain grate stoker having a coking zone, of a steam supply pipe, a valve in said pipe, branch pipes beyond said valve including pipe sections transversely disposed relative to said stoker and arranged in spaced relation, spaced apart distributor pipes communicating with each of said pipe sections, a nozzle at the upper end of each of said distributor pipes and disposed adjacent the bottom side of the upper run of said stoker to deliver steam against the fuel bed in the coking zone to break up the crust thereof, means for driving said stoker, and means operated by said stoker drive means for intermittently operating said valve.

FRED J. POSTEL. 

